Spinneret assembly



Aug. 28, 1962 R. A. TAIT SPINNERET ASSEMBLY 2 Sheets-Sheet 1 Filed July 27, 1960 Aug. 28, 1962 R. A. TAlT 3, 7

SPINNERET ASSEMBLY Filed July 27, 1960 2 Sheets-Sheet 2 United States Patent Ofifice 3,050,774 Patented Aug. 28,1962

3,050,774 SPINNERET ASSEMBLY Robert A. Tait, Richmond, Va., assiguor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed July 27, 1960, Ser. No. 45,569 4 Claims. (Cl. 18-8) This invention relates generally to the production of spun filaments from molten organic compositions and, more particularly, to a spinneret assembly useful in the spinning process.

In the melt-spinning of organic, polymeric materials such as nylon, it is customary to pass the molten polymer through a sand filter prior to extrusion through a spinneret. Such an assembly, in which the spun filaments are quenched with air below the spinneret, has been disclosed by Graves in U.S. Pat. No. 2,266,363. This procedure is entirely satisfactory when only a relatively small number of filaments is being spun. However, difficulties in maintaining filament uniformity have been encountered when spinning a large number of filaments, as in the production of high denier industrial yarns or staple tows. There have been various attempts to overcome these difi'i culties, e.g., by distributing the polymer in a uniform manner and at a uniform pressure. One such attempt, which involves the use of a rectangular spinneret and a plural cavity filter, has been disclosed by McCormick et al. in U.S. Patent No. 2,969,561.

The most important object of the present invention is to improve the uniformity of melt-spun filaments.

A further important object of the invention is to provide for the uniform distribution of polymer to the individual holes in a spinneret and for the elimination of stagnation zones in the spinneret assembly. These and other objectives are accomplished in a spinneret assembly which has superimposed filter block, distribution plate and spinneret plate elements. The filter block element has two or more filtration cavities each of which has a perforated bottom wall. In the successive elements, the holes are more frequent, smaller in diameter and staggered relative to the holes in an adjacent element. The hole pattern in the distribution plate covers a larger area and extends peripherally beyond the other hole patterns.

Other objectives will become apparent in the following specification wherein reference is made to the accompanying drawings in which:

FIGURE 1 is a fragmentary side view of the spinneret assembly of the invention, parts having been broken away and shown in section (along irregular line II of FIG. 2) to reveal details of construction;

FIGS. 2 and 3 are fragmentary sectional views taken on lines IIII and III-III, respectively, of FIG. 1; and

FIG. 4 is an end view of the assembly shown in FIG. 1, parts having been broken away and shown in section to illustrate the manner in which the assembly is located with respect to a spinning machine.

The embodiment of the spinneret assembly which has been chosen for illustration includes a lid 10, a filter block or sand holder 12, a distribution plate 14 and a spinneret plate 16. As best shown in FIG. 4, the lid has an upstanding rib 18 which fits in a groove 20 in a spinning machine 22 and is held in place by a plurality of screws 24. There is a screw 24, a gasket 26 and a flow passage 28 for each cavity 30 of the assembly. Lid 10, block 12 and plates 14, 16 have spacers 31, 33, 35 located therebetween and are sealed by gaskets 32, 34, 36. A fastener 38 extends through the plates and into block 12 to provide suitable support centrally of the assembly. The distribution zone 55 between plates 14, 16 is fitted with a pair of screens 40 and the assembly, including a peripheral ring beneath another hole.

member 4-2, is held together by a plurality of through bolts 44.

As illustrated, each pair of cavities 30 feeds into a .Zone 45 between the bottom wall 46 thereof and plate .14- which zone is defined by an opening 48 in gasket 34. The individual cavities 30 are elliptical in cross section and discharge through an elliptical pattern of equi-dimensional holes 59 passing through the associated bottom wall 46. Plate 14 is provided with a substantially rectangular hole pattern in which pattern the individual holes 52 are arranged in longitudinal rows and staggered transversely, i.e., with respect to the holes in adjacent rows. Equidirnensional holes 52 have a diameter substantially less than the minimum diameter of holes 50. Inthe assembled spinneret, holes 52 are also staggered with respect to holes 50 and their pattern extends peripherally beyond the pattern of holes 50, as shown in FIG. 2. Plate 16 is similarly provided with a substantially rectangular pattern of equi-dimensional spinneret holes 54 which, with respect to the distribution holes 52, are smaller in diameter and more frequent. The holes 54 are also arranged in longitudinal rows each of which lies substantially midway between two rows of distribution holes. It is apparent from FIG. 3 that the distribution hole pattern extends beyond the spinneret hole pattern in every direction.

The various hole patterns are arranged in such a manner that no distribution hole 52 or spinneret hole 54 is spaced and symmetrically staggered relative to the holes in the next adjacent row and, at the same time, are substantially equally spaced from the nearest distribution hole. The latter feature has been accomplished in part by varying the hole frequency in alternate rows of distribution holes 52. The combination of these features with the successive decrease in hole diameter from element to element and the greater peripheral extent of the distribution hole pattern insures an increased pressure drop across the successive elements 12 (4-6), 14, 16 and a substantially equal volumetric flow through each spinneret hole 54. r e

In operation, equal volumes of molten polymer are pumped to the passages 23 and through the filter medium 56 in each cavity 30 in much the same manner as has been described in the McCormick et al. patent. There is thus a substantially uniform flow through each hole 50 to the zone 45 above distribution'plate 14. In view of the staggered relationship between the holes 50, 52 and the location of certain holes 52 peripherally beyond the patterns of holes 51 all of zone 45 is swept by the polymer, there is no possibility of stagnation in that zone and there is a substantially equal pressure drop through each hole 52. The staggered relationship betweel holes 52, 54 and the frequent location of holes; 52 beyond the periphery of the spinneret hole patternsimilarly insures an equal flow through each spinneret hole 54 and the elimination of any stagnation in the dis tribution zone 55 between plates 14, 16.

The illustrated filter block 12 has a total of four cavities 30, only two of which have been shown in detail in FIGS. 13. It should be apparent, however, that each pair of cavities 30 discharges through the associated holes 50 to a single zone 45 which in turn discharges to a single zone 55 and that an identical flow arrangement is provided for the pair of cavities (not shown) located on the opposite side of screw 38. It is equally apparent that additional pairs of cavities could be provided, depending on the construction of the particular spinning machine to which the assembly is to be connected.

As noted previously, the use of plural sand cavities for the purpose 'of obtaining a uniform flow of the polymer melt therethrough has been described by McCormick The spinneret holes are equimay be made in the disclosed spinneret assembly without departing from the spirit of the present invention which is therefore intended to be limited only by the scope of the appended claims.

Having thus described the invention, what is claimed "as new and desired to be secured by Letters Patent is:

1. A spinneret assembly comprising superimposed filter block, distribution plate and spinneret plate Velements,isaid elements being spaced to present zones therebetween,-each elementbeing provided with a pattern of spaced, substantially equi-dimensional flow holes, the holes in the successive elements being more frequent and smaller diameter with the distribution hole pattern covering 'a larger area, extending peripherally beyond the other patterns, and being substantially conterminous with both zones, each distribution'hole alsobeing staggered with respect to the holes in the other elements, there being a" uniform density of holes throughout the area of each pattern.

2. The spinneret assembly of claim 1 wherein the filter block element is provided with at least two filtration cavities each having a bottom wall in which a separate pattern of filter block holes is located,,the distribution and spinneret hole patterns being uninterrupted, each distribution hole being communicable with each'filter block hole.

3. .A spinneret assembly comprising superimposed filter block, distribution plate and spinneret plate elements, said elementsbeing spaeedto presentzones-therebetween, each element being provided with a pattern of V substantially equi-dimensional flow holes, the holes in the distribution and spinneret elements being arranged in parallel rows with each ihole staggered relative to those of adjacent rows, e'achrow-ofspinneretholes being located between two'adjacent rows "of distribution holes, said distribution hole pattern covering alarger. area than the other patterns and'beingsubstantially conterrninous with both zones.

4. A spinneret assembly tom wall and "each plate being provided with a pattern of substantially'equidimensional flow 'holes th'e holes in the successive elements "beingmore frequent, smaller in diameter and-staggered irelativeto the holes in an adjacent element, the "pattern of'the distribution holes ex} tending peripherally-beyond the other patterns and being substantially conterminouswith'both zones, there being a substantially uniform density-of holes throughout the area of each pattern. a

References Cited in theifile of this patent UNITED STATES PATENTS 2,273,105 Heckert- ;Feb. 17,1942

2,408,713 Webb' Oct-1, 1946 2,589,870 pSale'et al Mar. 18,1952

2,792,122 Munch et a1 May 14, 1957 2,841,821 Phipps July S, 1958 1 2,969,561

Mc'Cormick et'al'. Jan; 31, 1961 I 7 comprising superimposed filter block, '-distribution"plate and "s'pirneret plate "elements, saidelerne'nts being spaced to present zones therebetweemsaidfilter blockelement including at leasttwo filti'ation cavities each having a bottom'wall, eajch 'bot-"' 

